[paraslash.git] / client_common.c

/*
 * Copyright (C) 1997-2013 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file client_common.c Common functions of para_client and para_audiod. */

#include <regex.h>
#include <sys/types.h>

#include "para.h"
#include "error.h"
#include "list.h"
#include "sched.h"
#include "client.cmdline.h"
#include "crypt.h"
#include "net.h"
#include "fd.h"
#include "sideband.h"
#include "string.h"
#include "client.cmdline.h"
#include "client.h"
#include "buffer_tree.h"
#include "version.h"

/** The size of the receiving buffer. */
#define CLIENT_BUFSIZE 4000

/**
 * Close the connection to para_server and deallocate per-command ressources.
 *
 * \param ct The client task.
 *
 * This frees all ressources of the current command but keeps the configuration
 * in \p ct->conf.
 *
 * \sa \ref client_close().
 */
void client_disconnect(struct client_task *ct)
{
        if (!ct)
                return;
        if (ct->scc.fd >= 0)
                close(ct->scc.fd);
        free_argv(ct->features);
        ct->features = NULL;
        sc_free(ct->scc.recv);
        ct->scc.recv = NULL;
        sc_free(ct->scc.send);
        ct->scc.send = NULL;
        btr_remove_node(&ct->btrn);
}

/**
 * Close the connection to para_server and free all resources.
 *
 * \param ct Pointer to the client data.
 *
 * \sa \ref client_open(), \ref client_disconnect().
 */
void client_close(struct client_task *ct)
{
        if (!ct)
                return;
        client_disconnect(ct);
        free(ct->user);
        free(ct->config_file);
        free(ct->key_file);
        client_cmdline_parser_free(&ct->conf);
        free(ct->challenge_hash);
        sb_free(ct->sbc);
        free(ct);
}

/**
 * The preselect hook for server commands.
 *
 * \param s Pointer to the scheduler.
 * \param t Pointer to the task struct for this command.
 *
 * The task pointer must contain a pointer to the initialized client data
 * structure as it is returned by client_open().
 *
 * This function checks the state of the connection and adds the file descriptor
 * of the connection to the read or write fd set of \a s accordingly.
 *
 * \sa register_task() client_open(), struct sched, struct task.
 */
static void client_pre_select(struct sched *s, struct task *t)
{
        int ret;
        struct client_task *ct = container_of(t, struct client_task, task);
        struct btr_node *btrn = ct->btrn;

        if (ct->scc.fd < 0)
                return;
        switch (ct->status) {
        case CL_CONNECTED:
        case CL_SENT_AUTH:
        case CL_SENT_CH_RESPONSE:
        case CL_SENT_COMMAND:
                para_fd_set(ct->scc.fd, &s->rfds, &s->max_fileno);
                return;

        case CL_RECEIVED_WELCOME:
        case CL_RECEIVED_PROCEED:
        case CL_RECEIVED_CHALLENGE:
                para_fd_set(ct->scc.fd, &s->wfds, &s->max_fileno);
                return;

        case CL_RECEIVING:
                ret = btr_node_status(btrn, 0, BTR_NT_ROOT);
                if (ret != 0) {
                        if (ret < 0)
                                sched_min_delay(s);
                        else
                                para_fd_set(ct->scc.fd, &s->rfds,
                                        &s->max_fileno);
                }
                return;
        case CL_SENDING:
                ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
                if (ret != 0) {
                        if (ret < 0)
                                sched_min_delay(s);
                        else
                                para_fd_set(ct->scc.fd, &s->wfds,
                                        &s->max_fileno);
                }
                return;
        }
}

static int client_recv_buffer(struct client_task *ct, fd_set *rfds,
                char *buf, size_t sz, size_t *n)
{
        int ret;

        if (ct->status < CL_SENT_CH_RESPONSE)
                return read_nonblock(ct->scc.fd, buf, sz, rfds, n);

        *n = 0;
        ret = sc_recv_buffer(&ct->scc, buf, sz);
        /*
         * sc_recv_buffer is used with blocking fds elsewhere, so it
         * does not use the nonblock-API. Therefore we need to
         * check for EOF and EAGAIN.
         */
        if (ret == 0)
                return -E_SERVER_EOF;
        if (ret == -ERRNO_TO_PARA_ERROR(EAGAIN))
                return 0;
        if (ret < 0)
                return ret;
        *n = ret;
        return 0;
}

static int send_sb(struct client_task *ct, void *buf, size_t numbytes,
                enum sb_designator band, bool dont_free)
{
        int ret, fd = ct->scc.fd;
        struct iovec iov[2];

        if (!ct->sbc) {
                struct sb_buffer sbb;
                sb_transformation trafo = ct->status < CL_RECEIVED_PROCEED?
                        NULL : sc_trafo;
                sbb = (typeof(sbb))SBB_INIT(band, buf, numbytes);
                ct->sbc = sb_new_send(&sbb, dont_free, trafo, ct->scc.send);
        }
        ret = sb_get_send_buffers(ct->sbc, iov);
        ret = xwritev(fd, iov, ret);
        if (ret < 0) {
                sb_free(ct->sbc);
                ct->sbc = NULL;
                return ret;
        }
        if (sb_sent(ct->sbc, ret)) {
                ct->sbc = NULL;
                return 1;
        }
        return 0;
}

static int recv_sb(struct client_task *ct, fd_set *rfds,
                struct sb_buffer *result)
{
        int ret;
        size_t n;
        sb_transformation trafo;
        void *trafo_context;
        struct iovec iov;

        if (!FD_ISSET(ct->scc.fd, rfds))
                return 0;
        if (ct->status < CL_SENT_CH_RESPONSE)
                trafo = trafo_context = NULL;
        else {
                trafo = sc_trafo;
                trafo_context = ct->scc.recv;
        }
        if (!ct->sbc)
                ct->sbc = sb_new_recv(0, trafo, trafo_context);
again:
        sb_get_recv_buffer(ct->sbc, &iov);
        ret = read_nonblock(ct->scc.fd, iov.iov_base, iov.iov_len, rfds, &n);
        if (ret < 0) {
                sb_free(ct->sbc);
                ct->sbc = NULL;
                return ret;
        }
        if (n == 0)
                return 0;
        if (!sb_received(ct->sbc, n, result))
                goto again;
        ct->sbc = NULL;
        return 1;
}


static char **parse_features(char *buf)
{
        int i;
        const char id[] = "\nFeatures: ";
        char *p, *q, **features;

        p = strstr(buf, id);
        if (!p)
                return NULL;
        p += strlen(id);
        q = strchr(p, '\n');
        if (!q)
                return NULL;
        *q = '\0';
        create_argv(p, ",", &features);
        for (i = 0; features[i]; i++)
                PARA_INFO_LOG("server feature: %s\n", features[i]);
        return features;
}

static int dispatch_sbb(struct client_task *ct, struct sb_buffer *sbb)
{
        int ret;
        const char *designator[] = {SB_DESIGNATORS_ARRAY};

        if (!sbb)
                return 0;
        if (sbb->band < NUM_SB_DESIGNATORS)
                PARA_DEBUG_LOG("band: %s\n", designator[sbb->band]);

        switch (sbb->band) {
        case SBD_OUTPUT:
                if (iov_valid(&sbb->iov))
                        btr_add_output(sbb->iov.iov_base, sbb->iov.iov_len,
                                ct->btrn);
                ret = 1;
                goto out;
        case SBD_DEBUG_LOG:
        case SBD_INFO_LOG:
        case SBD_NOTICE_LOG:
        case SBD_WARNING_LOG:
        case SBD_ERROR_LOG:
        case SBD_CRIT_LOG:
        case SBD_EMERG_LOG:
                if (iov_valid(&sbb->iov)) {
                        int ll = sbb->band - SBD_DEBUG_LOG;
                        para_log(ll, "remote: %s", (char *)sbb->iov.iov_base);
                }
                ret = 1;
                goto deallocate;
        case SBD_EXIT__SUCCESS:
                ret = -E_SERVER_CMD_SUCCESS;
                goto deallocate;
        case SBD_EXIT__FAILURE:
                ret = -E_SERVER_CMD_FAILURE;
                goto deallocate;
        default:
                PARA_ERROR_LOG("invalid band %d\n", sbb->band);
                ret = -E_BAD_BAND;
                goto deallocate;
        }
deallocate:
        free(sbb->iov.iov_base);
out:
        sbb->iov.iov_base = NULL;
        return ret;
}

static bool has_feature(const char *feature, struct client_task *ct)
{
        return find_arg(feature, ct->features) >= 0? true : false;
}

static int send_sb_command(struct client_task *ct)
{
        int i;
        char *command, *p;
        size_t len = 0;

        if (ct->sbc)
                return send_sb(ct, NULL, 0, 0, false);

        for (i = 0; i < ct->conf.inputs_num; i++)
                len += strlen(ct->conf.inputs[i]) + 1;
        p = command = para_malloc(len);
        for (i = 0; i < ct->conf.inputs_num; i++) {
                strcpy(p, ct->conf.inputs[i]);
                p += strlen(ct->conf.inputs[i]) + 1;
        }
        PARA_DEBUG_LOG("--> %s\n", command);
        return send_sb(ct, command, len, SBD_COMMAND, false);
}

/**
 * The post select hook for client commands.
 *
 * \param s Pointer to the scheduler.
 * \param t Pointer to the task struct for this command.
 *
 * Depending on the current state of the connection and the status of the read
 * and write fd sets of \a s, this function performs the necessary steps to
 * authenticate the connection, to send the command given by \a t->private_data
 * and to receive para_server's output, if any.
 *
 * \sa struct sched, struct task.
 */
static void client_post_select(struct sched *s, struct task *t)
{
        struct client_task *ct = container_of(t, struct client_task, task);
        struct btr_node *btrn = ct->btrn;
        int ret = 0;
        size_t n;
        char buf[CLIENT_BUFSIZE];

        ret = task_get_notification(t);
        if (ret < 0)
                goto out;
        if (ct->scc.fd < 0)
                return;
        switch (ct->status) {
        case CL_CONNECTED: /* receive welcome message */
                ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
                if (ret < 0 || n == 0)
                        goto out;
                ct->features = parse_features(buf);
                if (!has_feature("sideband", ct)) {
                        PARA_ERROR_LOG("server has no sideband support\n");
                        ret = -E_INCOMPAT_FEAT;
                        goto out;
                }
                ct->status = CL_RECEIVED_WELCOME;
                return;
        case CL_RECEIVED_WELCOME: /* send auth command */
                if (!FD_ISSET(ct->scc.fd, &s->wfds))
                        return;
                sprintf(buf, AUTH_REQUEST_MSG "%s sideband", ct->user);
                PARA_INFO_LOG("--> %s\n", buf);
                ret = write_buffer(ct->scc.fd, buf);
                if (ret < 0)
                        goto out;
                ct->status = CL_SENT_AUTH;
                return;
        case CL_SENT_AUTH:
                /*
                 * Receive challenge and session keys, decrypt the challenge and
                 * send back the hash of the decrypted challenge.
                 */
                {
                /* decrypted challenge/session key buffer */
                unsigned char crypt_buf[1024];
                struct sb_buffer sbb;

                ret = recv_sb(ct, &s->rfds, &sbb);
                if (ret <= 0)
                        goto out;
                if (sbb.band != SBD_CHALLENGE) {
                        ret = -E_BAD_BAND;
                        free(sbb.iov.iov_base);
                                goto out;
                }
                n = sbb.iov.iov_len;
                PARA_INFO_LOG("<-- [challenge] (%zu bytes)\n", n);
                ret = priv_decrypt(ct->key_file, crypt_buf,
                        sbb.iov.iov_base, n);
                free(sbb.iov.iov_base);
                if (ret < 0)
                        goto out;
                ct->challenge_hash = para_malloc(HASH_SIZE);
                hash_function((char *)crypt_buf, CHALLENGE_SIZE, ct->challenge_hash);
                ct->scc.send = sc_new(crypt_buf + CHALLENGE_SIZE, SESSION_KEY_LEN);
                ct->scc.recv = sc_new(crypt_buf + CHALLENGE_SIZE + SESSION_KEY_LEN,
                        SESSION_KEY_LEN);
                hash_to_asc(ct->challenge_hash, buf);
                PARA_INFO_LOG("--> %s\n", buf);
                ct->status = CL_RECEIVED_CHALLENGE;
                return;
                }
        case CL_RECEIVED_CHALLENGE:
                ret = send_sb(ct, ct->challenge_hash, HASH_SIZE,
                        SBD_CHALLENGE_RESPONSE, false);
                if (ret != 0)
                        ct->challenge_hash = NULL;
                if (ret <= 0)
                        goto out;
                ct->status = CL_SENT_CH_RESPONSE;
                goto out;
        case CL_SENT_CH_RESPONSE: /* read server response */
                {
                struct sb_buffer sbb;
                ret = recv_sb(ct, &s->rfds, &sbb);
                if (ret <= 0)
                        goto out;
                free(sbb.iov.iov_base);
                if (sbb.band != SBD_PROCEED)
                        ret = -E_BAD_BAND;
                else
                        ct->status = CL_RECEIVED_PROCEED;
                goto out;
                }
        case CL_RECEIVED_PROCEED: /* concat args and send command */
                {
                if (!FD_ISSET(ct->scc.fd, &s->wfds))
                        return;
                ret = send_sb_command(ct);
                if (ret <= 0)
                        goto out;
                ct->status = CL_SENT_COMMAND;
                return;
                }
        case CL_SENT_COMMAND:
                {
                struct sb_buffer sbb;
                ret = recv_sb(ct, &s->rfds, &sbb);
                if (ret <= 0)
                        goto out;
                if (sbb.band == SBD_AWAITING_DATA) {
                        ct->status = CL_SENDING;
                        free(sbb.iov.iov_base);
                        goto out;
                }
                ct->status = CL_RECEIVING;
                ret = dispatch_sbb(ct, &sbb);
                goto out;
                }
        case CL_SENDING:
                {
                char *buf2;
                size_t sz;
                ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
                if (ret < 0)
                        goto out;
                if (ret == 0)
                        return;
                if (!FD_ISSET(ct->scc.fd, &s->wfds))
                        return;
                sz = btr_next_buffer(btrn, &buf2);
                ret = sc_send_bin_buffer(&ct->scc, buf2, sz);
                if (ret < 0)
                        goto out;
                btr_consume(btrn, sz);
                return;
                }
        case CL_RECEIVING:
                {
                struct sb_buffer sbb;
                ret = btr_node_status(btrn, 0, BTR_NT_ROOT);
                if (ret < 0)
                        goto out;
                if (ret == 0)
                        return;
                /*
                 * The FD_ISSET() is not strictly necessary, but is allows us
                 * to skip the malloc below if there is nothing to read anyway.
                 */
                if (!FD_ISSET(ct->scc.fd, &s->rfds))
                        return;
                ret = recv_sb(ct, &s->rfds, &sbb);
                if (ret > 0)
                        ret = dispatch_sbb(ct, &sbb);
                goto out;
                }
        }
out:
        t->error = ret;
        if (ret < 0)
                btr_remove_node(&ct->btrn);
}

/**
 * Connect to para_server and register the client task.
 *
 * \param ct The initialized client task structure.
 * \param s The scheduler instance to register the client task to.
 * \param parent The parent node of the client btr node.
 * \param child The child node of the client node.
 *
 * The client task structure given by \a ct  must be allocated and initialized
 * by \ref client_parse_config() before this function is called.
 *
 * \return Standard.
 */
int client_connect(struct client_task *ct, struct sched *s,
                struct btr_node *parent, struct btr_node *child)
{
        int ret;

        PARA_NOTICE_LOG("connecting %s:%d\n", ct->conf.hostname_arg,
                ct->conf.server_port_arg);
        ct->scc.fd = -1;
        ret = para_connect_simple(IPPROTO_TCP, ct->conf.hostname_arg,
                                               ct->conf.server_port_arg);
        if (ret < 0)
                return ret;
        ct->scc.fd = ret;
        ret = mark_fd_nonblocking(ct->scc.fd);
        if (ret < 0)
                goto err_out;
        ct->status = CL_CONNECTED;
        ct->btrn = btr_new_node(&(struct btr_node_description)
                EMBRACE(.name = "client", .parent = parent, .child = child));
        ct->task.pre_select = client_pre_select;
        ct->task.post_select = client_post_select;
        ct->task.error = 0;
        sprintf(ct->task.status, "client");
        register_task(s, &ct->task);
        return 1;
err_out:
        close(ct->scc.fd);
        ct->scc.fd = -1;
        return ret;
}

/**
 * Parse a client configuration.
 *
 * \param argc Usual argument count.
 * \param argv Usual argument vector.
 * \param ct_ptr Filled in by this function.
 * \param loglevel If not \p NULL, the number of the loglevel is stored here.
 *
 * This checks the command line options given by \a argc and \a argv, sets
 * default values for the user name and the name of the rsa key file and reads
 * further options from the config file.
 *
 * Upon successful return, \a ct_ptr points to a dynamically allocated and
 * initialized client task struct.
 *
 * \return The number of non-option arguments in \a argc/argv on success,
 * negative on errors.
 */
int client_parse_config(int argc, char *argv[], struct client_task **ct_ptr,
                int *loglevel)
{
        char *home = para_homedir();
        int ret;
        struct client_task *ct = para_calloc(sizeof(struct client_task));

        *ct_ptr = ct;
        ct->scc.fd = -1;
        ret = -E_CLIENT_SYNTAX;
        if (client_cmdline_parser(argc, argv, &ct->conf))
                goto out;
        HANDLE_VERSION_FLAG("client", ct->conf);

        ct->config_file = ct->conf.config_file_given?
                para_strdup(ct->conf.config_file_arg) :
                make_message("%s/.paraslash/client.conf", home);
        ret = file_exists(ct->config_file);
        if (!ret && ct->conf.config_file_given) {
                ret = -E_NO_CONFIG;
                goto out;
        }
        if (ret) {
                struct client_cmdline_parser_params params = {
                        .override = 0,
                        .initialize = 0,
                        .check_required = 0,
                        .check_ambiguity = 0,
                        .print_errors = 0
                };
                ret = -E_BAD_CONFIG;
                if (client_cmdline_parser_config_file(ct->config_file,
                        &ct->conf, &params))
                        goto out;
        }
        ct->user = ct->conf.user_given?
                para_strdup(ct->conf.user_arg) : para_logname();

        if (ct->conf.key_file_given)
                ct->key_file = para_strdup(ct->conf.key_file_arg);
        else {
                ct->key_file = make_message("%s/.paraslash/key.%s",
                        home, ct->user);
                if (!file_exists(ct->key_file)) {
                        free(ct->key_file);
                        ct->key_file = make_message("%s/.ssh/id_rsa", home);
                }
        }

        if (loglevel)
                *loglevel = get_loglevel_by_name(ct->conf.loglevel_arg);
        PARA_INFO_LOG("loglevel: %s\n", ct->conf.loglevel_arg);
        PARA_INFO_LOG("config_file: %s\n", ct->config_file);
        PARA_INFO_LOG("key_file: %s\n", ct->key_file);
        ret = ct->conf.inputs_num;
out:
        free(home);
        if (ret < 0) {
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                client_close(ct);
                *ct_ptr = NULL;
        }
        return ret;
}

/**
 * Parse the client configuration and open a connection to para_server.
 *
 * \param argc See \ref client_parse_config.
 * \param argv See \ref client_parse_config.
 * \param ct_ptr See \ref client_parse_config.
 * \param loglevel See \ref client_parse_config.
 * \param parent See \ref client_connect().
 * \param child See \ref client_connect().
 * \param sched See \ref client_connect().
 *
 * This function combines client_parse_config() and client_connect(). It is
 * considered a syntax error if no command was given, i.e. if the number
 * of non-option arguments is zero.
 *
 * \return Standard.
 */
int client_open(int argc, char *argv[], struct client_task **ct_ptr,
                int *loglevel, struct btr_node *parent, struct btr_node *child,
                struct sched *sched)
{
        int ret = client_parse_config(argc, argv, ct_ptr, loglevel);

        if (ret < 0)
                return ret;
        if (ret == 0) {
                ret = -E_CLIENT_SYNTAX;
                goto fail;
        }
        ret = client_connect(*ct_ptr, sched, parent, child);
        if (ret < 0)
                goto fail;
        return 1;
fail:
        client_close(*ct_ptr);
        *ct_ptr = NULL;
        return ret;
}